FFI & II: The PlayStation remakes exhibit the best 2D graphics to be found in a Final Fantasy game, plus incredibly affecting synth-orchestrated soundtracks.

FFIII: As a game released late in the Famicom's life, the original is ever impressive for what it achieves as the final 8-bit entry in the series. It's much faster-paced than the remake, as well as being better-looking (ironically). The fan-translated ROM is your best bet.

FFIV: The PlayStation port has a revised translation (it makes sense, unlike the SNES original, but it's not toothless like the GBA script is) and all the gameplay features that had been removed from the original localization. It does retain the same aesthetics as the original, though, which have never really been improved upon.

FFV: Like FFIV, the PlayStation port earns points for having identical aesthetics, but its localization is pretty lackluster. Again, it's probably best to go with the fan-translated ROM.

FFVI: The PlayStation port removes some censorship, but it has abysmal load times, so that's right out. The GBA port, as with other games, has had its assets thoroughly downgraded and washed out, and that goes double for this game's amazing soundtrack, which some might say has been "raped to death." I would advise the original SNES version.